This invention relates to alarm systems--for example, theft or intruder alarms--for vehicles and other movable entities such for example as motor cars, trucks, caravans, boats and even, simply, a movable alarm system aggregate per se which can be made portable so as to be carried around a plurality of fixed structures such as building sites.
Alarm systems are known in which a triggered alarm actuates an autodialler system which in turn communicates via a telephone or radio link to a computer. Such systems identify the location of the installation by a recorded message, either a recorded voice message or a digitally encoded message, and also can identify the problem being encountered, whether it be a fire, intruder or whatever, as well, in more sophisticated systems, as giving zonal information useful to the police or other security organisation monitoring the alarm system to locate the problem in a large installation.